Abstract
Anabaena PCC 7120 heterocysts undergo at least three programmed DNA rear-rangements that affect the nitrogen-fixation genes nifD and fdxN, and the uptake hydrogenase gene hupL RT-PCR showed that hupL is expressed only after heterocysts have formed. An open reading frame that encodes a product similar to hupS or hupU is upstream of hupL. A 10.5-kb DNA element interrupts the hupL open reading frame and is excised during heterocyst differentiation. Correct expression of the presumed hupSL operon requires both transcriptional regulation and excision of the element. The hupL element encodes its own site-specific recombinase, XisC, which is 46% identical to the predicted XisA recombinase present on the PCC 7120 nifD element. The XisA and XisC proteins show sequence similarity to the catalytic domains of the integrase family of site-specific recombinases and contain the absolutely conserved catalytic Tyr residue. However, the Anabaena recombinases represent a distinct subset of the integrase family.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
